Frequency converter



FIG. 1 is a first perspective view of a frequency converter showing our new and ornamental design,

FIG. 2 is a second perspective view thereof,

FIG. 3 is a front view thereof,

FIG. 4 is a rear view thereof,

FIG. 5 is a first side view thereof,

FIG. 6 is an opposite, second side view thereof,

FIG. 7 is a first end view thereof; and,

FIG. 8 is an opposite, second end view thereof. 

CLAIM The ornamental design for a frequency converter, as shown and described. 